Tamaren

I'm in the last few stages of getting my '81 L-jet in tip-top shape, and ive been fighting this since I got the car. Things have improved it, but not solved it.

When it is cold, holds rock steady at 1100RPM. when it is at normal operating temperature, it varies 100RPM in either direction off 900 RPM.
Also, during a steady acceleration, there is a noticeable hesitation or miss, and a pretty major one at that. Hard accelerations it behaves better, but is still sometimes there.

Things that it is not, because I have replaced them:
Fuel Pump
Fuel Filter
Fuel Lines
Injectors (rebuilt and pressure tested)
Front pressure damper
All vacuum lines (steady 17" mercury from front vacuum line, so no leaks)
spark plugs
spark plug wires are not new, but in good shape, along with distributor
Engine wiring harness

Things I think could be the culprit:
O2 sensor
Barn door sender
Rear fuel pressure regulators
L-jet box
Fuel injection relay
A/F ratio?

Is there something I'm missing? I'm out of ideas. I bought the car a year ago, and was doing it the same as now, with an entirely rebuilt fuel system and good spark.

This forum is of great help, and I always appreciate the knowledge here.

Socal_Tom

Bump

Guy

Flucuations in idle can typically be caused by vacuum leaks or in a similar vain an overly lean mixture. Check the barn door seal and the plenum runners at the bases.

Shawn Stanford

I just finished a TB/cam seal change in my '82, I'm having the same issue. I was planning on checking timing next, did you do that?

Tamaren

Pulled plugs, yes I am running lean. Replaced o2 sensor, helped a lot, will check bottom of plenum and barn door next.

My timing is fine, I checked that when I did timing belt!